JP4729715B2 - Automatic voltage regulator {AUTOMATIC VOLTAGE REGULATOR} - Google Patents

Description

【Technical field】
[0001]
The present invention relates to an automatic voltage regulator, and more particularly,
The present invention relates to an automatic voltage regulator capable of precisely controlling an output voltage level using a toroidal autotransformer.
[Background]
[0002]
An automatic voltage regulator using a toroidal transformer can be implemented using various transformer windings.
In any case, the output voltage is determined by the windings of the primary and secondary coils.
A variety of voltages can be output by winding a coil to match the available voltage or by placing several output taps.
[0003]
For example, the autotransformer is illustrated in FIG.
Various levels of voltage can be output by placing a plurality of taps (a, b, c) on the excitation winding (200) excited by the main winding (100).
If a voltage of 220V is applied to the main winding (100), a 20V voltage is applied across the main winding (100)
If each tap of the excitation winding (200) is designed to depressurize by 5V,
From the first tap (a), a voltage of 200 V, from the second tap (b) to 205 V, and from the third tap (c), a voltage of 210 V can be output to the output terminal.
0004
Thus, the conventional automatic voltage regulator has a discrete output voltage with a large deviation,
For example, in the above example, it is designed to selectively output from output voltages of 200V, 205V, and 210V with a deviation of 5V.
The situation is that the precise voltage regulation that the user wants to use cannot be provided.
[0005]
As described above, the conventional automatic voltage regulator lacking in precision gives a great dissatisfaction to the user.
An example of the case of a power saving device using an automatic voltage regulator that lacks precision will be described in detail.
[0006]
In the case of a high-rise apartment on the 15th floor, the switchboard is in the basement, about 235 volts is provided on the first floor, but the supply voltage decreases as you go to the higher floor,
A voltage of about 205 volts is provided on the 15th floor.
In general, home appliances can operate stably when supplied with a voltage of 205 volts,
When installing and using a power-saving device that reduces about 10 volts for each household,
In households with a voltage of 215 or less, the use of an inappropriate power-saving device cannot guarantee the lower limit of 205 volts, which is a stable voltage.
On the other hand, on the top floor, the actual situation is that boosting is required so that a stable voltage is maintained sustainably.
[007]
Therefore, in the case of a high-rise apartment, there is a large deviation between the lower floor and the higher floor where the system voltage provided to the customer is
It is divided into floors that require decompression to save power and floors that need boost to provide a stable voltage.
It is a fact that users can not control precisely while satisfying all the wide deviations, and the users feel very inconvenient.
[0008]
The present invention solves the problems of the prior art and provides an automatic voltage regulator that can provide a very precise voltage level and an appropriate voltage.
[0009]
On the other hand, in order for the automatic voltage regulator in the conventional power electronic system to operate, a main transformer, an excitation transformer, a detection transformer, a high-sensitivity effective value detection circuit,
It requires many complicated stages, such as a high-speed A / D converter and a triac switching circuit.
As a result, it is applied only in special cases such as expensive experimental equipment and is expensive, so there is no marketability available to the general public.
[0010]
Since such a complex device cannot operate normally in an environment where the frequency and level of the system voltage are different,
There was a problem that the production of the product had to proceed separately in consideration of the power environment.
[0011]
However, the present invention is operated with a simple structure without using a power semiconductor circuit or the like, and can perform precise voltage adjustment regardless of the power environment.
[0012]
On the other hand, the conventional automatic voltage regulator selectively outputs a discrete output voltage level with a large deviation,
This is because the output voltage is output from a tap fixedly formed on the secondary coil.
[0013]
Moreover, the cause of such a technical limitation can be known from the fact that the winding method for the toroidal core has been operated with a very limited limit.
At present, the toroidal core has a main winding, and an exciting winding is formed by a method of forming an input / output tap while winding a coil of a certain thickness around the main winding.
If a non-conductive coil is inserted between the toroidal core main winding and the excitation winding,
There is a problem that smoke is generated in the coil inserted in the middle of operation,
Only the exciting windings connected in series from the tap and the main winding for exciting them are wound.
[0014]
However, the present invention improves the conventional winding method of the toroidal core so that various levels of induced voltage can be output.
SUMMARY OF THE INVENTION
[Problems to be solved by the invention]
[0015]
The present invention is based on the above-described contents, and is intended to provide an automatic voltage regulator capable of outputting a continuous voltage level and capable of precise voltage adjustment.
[Means for Solving the Problems]
0016
The above object is to provide an automatic voltage regulator for converting an input voltage applied to an input terminal according to the present invention and applying it to an output terminal.
One end is connected to the input end and the other end is connected to the output end,
A main winding portion including a plurality of main windings and a plurality of first switches for switching so that the plurality of main windings are selectively connected in series;
An excitation winding excited in at least one main winding connected in series by the first switch in the main winding;
A second switch for selectively connecting one end of the excitation winding to one of the reference potential and the output end;
A third switch for connecting one of the reference potential and the input terminal to the other end of the excitation winding;
And an automatic voltage regulator comprising a control unit for adjusting a level of an output voltage output to the output terminal by switching control of the plurality of first switches, the second switch, and the third switch. Achieve.
[0017]
The automatic voltage regulator also includes a level measuring unit that measures the level of the input voltage input to the input terminal,
When the predetermined target voltage is greater than the level of the input voltage measured by the level measurement unit,
In response to the voltage difference between the target voltage and the measured level, switching control of the plurality of first switches,
The second switch controls to connect one end of the excitation winding with the reference potential,
Controlling the third switch to connect the other end of the excitation winding to the input end;
When the target voltage is smaller than the level of the input voltage, the plurality of first switches are controlled to switch according to the voltage difference between the target voltage and the measured level, and the second switch is the excitation winding. And controlling one end of the
The third switch can be controlled to connect the other end of the excitation winding to the reference potential.
[0018]
The automatic voltage regulator also includes a user input unit for inputting the target voltage from the user.
A bypass path for bypassing the input voltage to the main winding;
And a bypass switch for switching whether or not the bypass path is connected,
When the level of the input voltage corresponds to the target voltage, it is desirable to control so that the input voltage can be bypassed by turning on the bypass switch.
[0019]
Then, the excitation winding is wound around the toroidal core, and the plurality of main windings wind the excitation winding,
The plurality of main windings are wound so as not to overlap the toroidal core.
[0020]
According to another aspect of the present invention, there is provided an automatic voltage regulator that converts an input voltage applied to an input terminal and outputs the converted voltage to an output terminal.
One end is connected to the input end and the other end is connected to the output end,
A main winding portion including a plurality of main windings and a plurality of first switches for switching so that the plurality of main windings are selectively connected in series;
An excitation winding having one end connected to the output end and excited by at least one main winding connected in series by the first switch in the main winding portion;
And an automatic voltage regulator including a control unit for adjusting a level of an output voltage output to the output terminal by switching control of the plurality of first switches.
[0021]
The automatic voltage regulator also includes a level measuring unit that measures the level of the input voltage input to the input terminal,
When the target voltage is lower than the input voltage level, the control unit
The plurality of first switches are subjected to switching control corresponding to the voltage difference between the target voltage and the measured level.
[0022]
The automatic voltage regulator of the present invention is a bypass path for bypassing the input voltage to the main winding part;
And a bypass switch for switching whether or not the bypass path is connected,
When the input voltage level corresponds to the target voltage,
It is desirable to control the input voltage to be bypassed by turning on the bypass switch.
【The invention's effect】
[0023]
The present invention enables precise voltage control so that the voltage level used by the user is output,
Various applications as power saving operation and voltage booster can be made precisely.
In particular, it is possible to provide the input voltage by increasing / decreasing the target voltage to the target voltage within an error range of 1 volt or less.
[0024]
In addition, the present invention comprises a simple relay switching circuit and eliminates the semiconductor switching element,
It can be adapted and operated in different grid environments and requires no separate changes.
[0025]
In addition, the present invention does not form many output taps or a large number of auxiliary coils, and can adjust the voltage in a wider range.
At the same time, any value can be accurately output in the voltage adjustment range.
BEST MODE FOR CARRYING OUT THE INVENTION
[0026]
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0027]
FIG. 2 is a schematic internal configuration diagram of the automatic voltage regulator (AVR) according to the first embodiment of the present invention.
[0028]
Referring to FIG. 2, the automatic voltage regulator includes a plurality of main windings (1a0 to 1an) and a main winding portion (1) having a first switch (1b0 to 1bn),
Excitation winding (2), 2nd switch (3), 3rd switch (4), bypass switch (5), level measurement unit (6), input unit (7) and control unit (8)
It is comprised including.
[0029]
One end of the main winding (1) is connected to the input end (L1) into which the input voltage is drawn, and the other end is connected to the output end (L2).
The circuit connection relationship between both ends (the connection relationship of the main windings (1a0 to 1an)) is determined by how the plurality of first switches (1b0 to 1bn) are switching-connected.
That is, as shown in the figure, the corresponding main winding (1a0-1an) is connected to one end of the main winding (1a0-1an) depending on whether the first switch (1b0-1bn) is connected to the main winding portion (1). It is determined whether or not it is included as a constituent element of a series circuit that connects both ends of each other.
In the following, the first switch (1b0 to 1bn) is connected to one end of the main winding (1a0 to 1an), and the main winding (1a0 to 1an) becomes part of the series circuit, increasing the total number of main ticket lines The case where it is done is called "series mode"
On the other hand, the case where the main winding (1a0 to 1an) is insulated from the series circuit is referred to as “insulation mode”.
[0030]
By switching control of multiple first switches (1b0-1bn) individually in series mode or insulation mode,
The main winding (1a0 to 1an) included in the series circuit connecting both ends of the main winding (1) can be selected,
As a result, the total number of main ticket lines included in the series circuit can be controlled.
[0031]
Particularly in this embodiment, the plurality of main ticket lines (1a0 to 1an) are 2 ⁰ = 1, 2 ¹ = 2, 2 ² = 4, 2 ³ = 8, ..., 2 ⁿ T (turns)
Here, n is a natural number) and has a number of turns.
Therefore, by combining the main windings (1a0-1an) to form a series circuit,
The total number of main ticket lines of the series circuit between both ends of the main winding (1) is adjusted so as to correspond to an arbitrary natural number within a range that can be expressed.
For example, if n = 10, the number of windings corresponding to an arbitrary natural number within 1 to 2047 can be adjusted.
[0032]
The exciting winding (2) is excited by main windings (1a0 to 1an) connected in series between both ends of the main winding portion (1).
Therefore, although the number of windings of the excitation winding (2) is fixed, the voltage excited in the excitation winding (2) by the total number of main ticket wires included in the series circuit of the main winding portion (1) The size will change.
0033
The second switch (3) is for selectively connecting one end (2a) of the excitation winding (2) to one of the reference potential (N) and the output end (L2). The third switch (4) is for selectively connecting the other end (2b) of the excitation winding (2) to one of the reference potential (N) and the input end (L1).
[0034]
Specifically, if the second switch (3) is switched to connect one end (2a) of the excitation winding (2) to the output end (L2),
In conjunction with this, the third switch (4) is always switched to connect the other end (2b) of the excitation winding (2) to the reference potential (N).
On the other hand, if the second switch (3) is switched to connect one end (2a) of the excitation winding (2) to the reference potential (N),
In conjunction with this, the third switch (4) is always switched to connect the other end (2b) of the excitation winding (2) to the input end (L1).
[0035]
This is a mode in which the induced voltage formed in the excitation winding (2) pressurizes the input voltage (hereinafter referred to as “pressurization mode”) and a mode in which the induced voltage reduces the input voltage (hereinafter referred to as “depressurization mode”). Say) for conversion between.
Which mode is used under what conditions will be explained below,
Here, only the fact that the second switch (3) and the third switch (4) are linked and switched in a certain manner for switching between these modes will be described.
[0036]
In this embodiment, the winding direction of the excitation winding (2) and the main winding (1a0-1an) is fixed to the toroidal core,
Especially for the example where one end (2a) of the excitation winding (2) is connected to the output end (L2) and the other end is connected to the reference potential (N) so as to operate in the decompression mode. explain.
[0037]
Referring again to FIG. 2, the bypass switch (5) is used to directly connect or insulate the input terminal (L1) with the output terminal (L2).
Provide a path to bypass the input voltage when trying to output without changing the input voltage.
[0038]
The level measuring unit (6) is for measuring the level of the voltage input from the input terminal (L1), and measures and outputs the peak value or the actual effect value.
[0039]
The input unit (7) is for inputting a target voltage to be output by the user.
A panel in which an input switch such as an up / down key is formed, and a receiving device for receiving a remote control command may be variously implemented.
The target voltage may be a default value, a value that was previously input by the user and stored, or a value that is newly updated during operation.
[0040]
* The control unit (8) compares the input voltage measured by the level measurement unit (6) with the target voltage,
The switching control operation of the first to third switches (1b0 to 1bn, 3, 4) and the bypass switch (5) is performed so that the magnitude of the input voltage becomes the target voltage.
[0041]
With reference to the operation of the control unit (8), the general operation of the automatic voltage regulator started in FIG. 2 will be described separately according to the magnitude of the target voltage and the input voltage.
[0042]
* To facilitate understanding, refer to the experimental data shown in Table 1.
<Table 1> shows that the number of excitation windings (2) is fixed at 500T and the target voltage is set to 220 [V], and the input voltage is input in the range of 187 to 220 [V]. Is an experimental data showing how the total number of windings of the main winding part (1) is determined by.
[0043]
[0044]
<table 1>
[0045]
1) When the target voltage (220V) matches the input voltage (220V)-Bypass mode:
[0046]
Control is performed so that the input voltage is output as it is. Therefore,
The control unit (8) turns on the bypass switch (5) and controls the input voltage to bypass the main winding unit (1) and output to the output terminal (L2).
(Refer to section 1 in Table 1)
[0047]
2) When the target voltage (220V) is higher than the input voltage-Pressurization mode:
[0048]
The input voltage must be boosted to the target voltage.
[0049]
Therefore, the control unit (8) controls the first to third switches and the bypass switch (5) so that the input voltage is boosted and output.
[0050]
Specifically, the control unit (8) turns off the bypass switch (5),
Control the second switch (3) so that one end (2a) of the excitation winding (2) is connected to the reference potential (N),
The third switch (4) is controlled so that the other end (2b) of the excitation winding (2) is connected to the input end (L1) (pressurization mode).
[0051]
On the other hand, the control unit (8) sets the induction voltage level of the excitation winding (2) that becomes the magnitude of pressurization so as to compensate for the difference between the input voltage level measured by the level measurement unit (6) and the target voltage. adjust.
For this purpose, the control unit (8) calculates the total number of windings of the main winding unit (1) in which the voltage corresponding to the voltage difference is induced,
The first switches (1b0 to 1bn) are controlled so that the main windings (1a0 to 1an) combined correspondingly form a series circuit.
That is, the corresponding first switches (1b0 to 1bn) are selectively controlled to be switched between the series mode and the insulation mode so that the combination of the calculated total number of windings becomes possible.
[0052]
Referring to Table 1, as the input voltage is further reduced and the voltage difference is increased with respect to the target voltage of 220 V, the number of turns of the entire main winding portion (1), that is, the main windings connected in series (1a0 It can be confirmed that if the total number of windings of ˜1an) is further increased, the magnitude of the voltage induced in the excitation winding (2) is also increased and voltage compensation is possible.
For example, when the input voltage is 219 [V], the voltage difference is 1 [V] and the required number of main ticket lines is 2 [T]
When the input voltage is 210 [V], the voltage difference is 10 [V] and the required number of main ticket lines is 24 [T].
[0053]
3) If the target voltage is lower than the input voltage-decompression mode:
[0054]
The control unit (8) controls the first to third switches and the bypass switch (5) so that the input voltage is reduced and output.
[0055]
Specifically, the control unit (8) turns off the bypass switch (5),
Control the second switch (3) so that one end (2a) of the excitation winding (2) is connected to the output end (L2),
The third switch (4) is controlled so that the other end (2b) of the excitation winding (2) is connected to the reference potential (N).
[0056]
On the other hand, the control unit (8) adjusts the induced voltage level of the excitation winding (2), which is reduced in magnitude, to compensate for the difference between the input voltage level measured by the level measurement unit (6) and the target voltage. To do.
For this purpose, the control unit (8) calculates the total number of windings of the main winding unit (1) so that the voltage corresponding to the voltage difference that must be compensated is induced in the excitation winding (2), and The first switches (1b0 to 1bn) are controlled such that the corresponding main windings (1a0 to 1an) form a series circuit.
That is, the corresponding first switches (1b0 to 1bn) are selectively switched to the series mode and the insulation mode so that the calculated total number of windings can be combined.
[0057]
Referring back to Table 1, it can be seen that the required number of main ticket lines is proportional to the absolute value of the voltage difference between the target voltage and the input voltage.
Therefore, the magnitude relationship between the input voltage and the target voltage only relates to the switching mode of the second switch (3) and the third switch (4), and does not cause the required number of main windings to fluctuate.
[0058]
If you compare the columns of `` Voltage difference '', `` Voltage fluctuation rate '' and `` Number of required main ticket lines '' in the column of <Table 1>,
It can be seen that there is a proportional relationship between them. That is, as the voltage difference increases, the voltage level that must be compensated for increases. Therefore, it is understood that control is performed to increase the total number of main ticket lines in order to increase the induced voltage of the excitation winding (2).
[0059]
<Table 1> shows not only the voltage difference in 1 [V] units.
While showing that the voltage difference of less than 1 [V] is compensated,
This may vary depending on the number of windings of the excitation winding (2) and the core dose.
Therefore, depending on the specifications, the data for the voltage difference and the required number of main ticket lines are saved in advance,
The control unit (8) can selectively control the first switches (1b0 to 1bn) as a series mode or an insulation mode based on data stored in advance.
[0060]
It will be understood that the configuration of FIG. 2 according to the first embodiment of the present invention can be variously modified within the scope of the present invention.
[0061]
For example, it can be seen that the number of windings of the main windings (1a0 to 1an) is determined by 2 ^k (k = 0, 1, 2, 3,...), But other combinations are possible.
For example, if the number of windings and the core dose of the excitation winding (2) are determined,
2 ^j [V] (j = 0, 1, 2, 3,...) The number of windings of the main windings (1a0 to 1an) can be formed so as to correspond to the voltage difference in units.
In this case, adjustment is difficult for voltages below 1 [V], but it is possible to compensate for voltage differences in units of 1 [V].
[0062]
It can also be seen that the number of windings of the excitation winding (2) may not be fixed.
In this case, it is necessary to appropriately select the number of main ticket lines and the number of exciting windings, and this can be experimentally determined in advance.
[0063]
According to another embodiment of the present invention, even when the number of main ticket lines is not predetermined by the voltage difference,
It is possible to increase or decrease the number of windings connected in series by measuring the output voltage level and feeding back this value to track the appropriate number of windings.
[0064]
As described above, the automatic voltage regulator of the present invention is not limited to an environment that requires power saving,
Even when the power supply environment is poor and the input voltage does not reach the rated voltage of the electrical product,
The rated voltage can be provided by automatically boosting the input voltage.
[0065]
The present invention can select the step-up or step-down of the output voltage by switching the second switch (3) and the third switch (4),
By switching the first switches (1b0 to 1bn), the range of pressure increase and decrease can be increased.
[0066]
FIG. 3 is a schematic circuit diagram of an automatic voltage regulator according to the second embodiment of the present invention.
It can be easily confirmed that the internal configuration is almost the same as FIG.
Therefore, the second embodiment will be described focusing on the structural features of FIG. 3 different from those of FIG. 2 and the first embodiment.
[0067]
Referring to FIG. 3, one end of the excitation winding is fixedly connected to the output end,
It can be seen that the other end is fixedly connected to the reference potential end.
[0068]
Therefore, as mentioned in the first embodiment, the automatic voltage regulator of FIG. 3 is used only in a system that strongly boosts or bypasses the input voltage, and cannot be used for boosting.
[0069]
These application limits are based on actual industrial applications, and demands from consumers who want to save power,
This is in consideration of infrastructure with stable power supply.
[0070]
Even if the options for the working method are limited compared to the first embodiment,
Operation in the above-described decompression mode is possible, and precise control in units of 1 [V] is still possible.
[0071]
FIGS. 4a and 4b are schematic diagrams for explaining the wire system of the toroidal transformer according to the first and second embodiments of the present invention.
[0072]
Referring to FIG. 4a, the excitation winding (2) is first scored so as to be distributed throughout the toroidal core.
Next, as shown in FIG. 4 b, a plurality of main windings (1 a 0 to 1 an) are wound on the excitation winding (2), that is, so as not to overlap each other while covering the excitation winding (2). Formed. Main windings (1a0 to 1an) Each of the main windings is formed so as to have a starting portion and a ending portion of the winding, and is counted in the unit in which the starting portion and the ending portion of the winding are formed. (1a0-1an) is distinguished.
[0073]
As mentioned above, the conventional toroidal transformer is wound with the excitation winding (2) on the main winding (1a0 ~ 1an)
So that you can get induced voltages of different voltage levels,
As a result, the degree of pressure increase and decrease was fixed or very limited.
[0074]
However, since the toroidal transformer of the present invention is distributed and wound on the upper layer of the excitation winding (2) so that the main winding (1a0 to 1an) is not overlapped, the selection range is much wider than before. A level output voltage can be obtained.
[0075]
Although several embodiments of the present invention have been illustrated and described so far, those skilled in the art having ordinary knowledge in the technical field to which the present invention pertains can modify this embodiment without departing from the principles and spirit of the present invention. It should be understood that there is a possibility of doing.
[0076]
For example, the first switch of the present invention is for variably determining the number of main windings connected in series in the circuit,
The installation position may be changed differently from FIG. 2 and FIG.
Specifically, even if a large number of taps are formed in the main winding and one of these taps is connected to the input end or the output end,
It is possible to selectively vary the winding of the main winding.
[0077]
Accordingly, the present invention must be construed as including all that the first switch is arranged to determine the final number of turns of the main winding, and such variations are within the scope of the present invention. Must be seen as a thing.
[0078]
The scope of the invention is determined by the appended claims and their equivalents.
[Brief description of the drawings]
79 is a schematic circuit diagram for explaining the output of a plurality of voltage levels from a plurality of taps of an excitation winding in a conventional autotransformer;
FIG. 2 is a schematic internal configuration diagram of an automatic voltage regulator (AVR) capable of adjusting an output voltage in voltage units corresponding to 1 [turn] according to the first embodiment of the present invention;
81 FIG. 3 is a schematic internal configuration diagram of an automatic voltage regulator according to a second embodiment of the present invention; and 82 FIGS. FIG.

Claims (9)

In the automatic voltage regulator that converts the input voltage applied to the input terminal and outputs it to the output terminal,
One end is connected to the input end and the other end is connected to the output end,
A main winding portion including a plurality of main windings and a plurality of first switches for switching so that the plurality of main windings are selectively connected in series;
An excitation winding excited in at least one main winding connected in series by the first switch in the main winding;
A second switch for selectively connecting one end of the excitation winding to one of a reference potential and the output end;
A third switch for connecting one of the reference potential and the input terminal to the other end of the excitation winding;
And an automatic voltage regulator comprising a control unit for adjusting a level of an output voltage output to the output terminal by switching control of the plurality of first switches, the second switch, and the third switch. In item 1,
Including a level measuring unit for measuring the level of the input voltage input to the input terminal,
The control unit
When the predetermined target voltage is larger than the level of the input voltage measured by the level measuring unit, the plurality of first switches are controlled to switch in response to the voltage difference between the target voltage and the measured level. Controlling the second switch to connect one end of the excitation winding to the reference potential, and controlling the third switch to connect the other end of the excitation winding to the input end;
When the target voltage is smaller than the level of the input voltage, the plurality of first switches are controlled to switch according to the voltage difference between the target voltage and the measured level, and the second switch An automatic voltage regulator comprising: controlling one end of a line to be connected to the output end, and controlling the third switch to connect the other end of the excitation winding to the reference potential. In the first term or the second term,
The automatic voltage regulator characterized by including the input part for inputting the said daily target voltage from a user. In the first term or the second term,
A bypass path for bypassing the input voltage with respect to the main winding portion; and a bypass switch for switching whether or not the bypass path is connected,
An automatic voltage regulator, wherein when the level of the input voltage corresponds to the target voltage, the bypass switch is turned on to control the input voltage to be bypassed. In the first term or the second term,
The excitation winding is wound around the toroidal core,
The automatic voltage regulator, wherein the plurality of main windings wind the excitation winding, and the plurality of main windings are wound so as not to be in contact with each other on the toroidal core. In the automatic voltage regulator that converts the input voltage applied to the input terminal and outputs it to the output terminal,
One end is connected to the input end and the other end is connected to the output end,
A main winding portion including a plurality of main windings and a plurality of first switches for switching so that the plurality of main windings are selectively connected in series;
One end is connected to the output end, the other end is connected to a reference potential,
An excitation winding excited in at least one main winding connected in series by the first switch in the main winding;
And an automatic voltage regulator comprising a control unit for adjusting a level of an output voltage output to the output terminal by switching control of the plurality of first switches. In item 6, including a level measurement unit for measuring the level of the input voltage input to the input terminal,
The control unit, when the level of the input voltage is greater than a predetermined target voltage,
An automatic voltage regulator comprising: switching control of the plurality of first switches in response to a voltage difference between the target voltage and the measured level. In item 6 or 7,
A bypass path for bypassing the input voltage with respect to the main winding; and a bypass switch for switching whether the bypass path is connected or not,
An automatic voltage regulator, wherein when the input voltage level corresponds to the target voltage, the bypass switch is turned on to control the input voltage to be bypassed. In item 6 or 7,
The excitation winding is wound around the toroidal core,
The automatic voltage regulator, wherein the plurality of main windings wind the excitation winding, and the plurality of main windings are wound so as not to be in contact with each other on the toroidal core.